zoukankan      html  css  js  c++  java
  • boost asio异步读写网络聊天程序客户端 实例详解

    boost官方文档中聊天程序实例讲解

    数据包格式chat_message.hpp

    <pre name="code" class="cpp"><h3>数据包chat_message.hpp</h3>
    // chat_message.hpp
    // ~~~~~~~~~~~~~~~~
    //
    // Copyright (c) 2003-2013 Christopher M. Kohlhoff (chris at kohlhoff dot com)
    //
    // Distributed under the Boost Software License, Version 1.0. (See accompanying
    // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
    //实例源于http://www.boost.org/doc/libs/1_55_0/doc/html/boost_asio/examples/cpp03_examples.html 文档中没有注释,自己在///开始看的时候也走了点弯路,本文对该源码写了详细的注释,希望能让后来者们少走些弯路。
    //首先看看数据包的结构:
    //数据包分为两个部分,首先是报头占4bytes,每一byte表示一个数字,也就是最多能表示的出9999,不足在前填0;
    // 数据包头的数字表示数据部分的长度大小。

    #ifndef CHAT_MESSAGE_HPP
    #define CHAT_MESSAGE_HPP

    #include <cstdio>
    #include <cstdlib>
    #include <cstring>

    class chat_message
    {
    public:
    enum { header_length = 4 };
    enum { max_body_length = 512 };

    chat_message()
    : body_length_(0)
    {
    }

    const char* data() const
    {
    return data_;
    }

    char* data()
    {
    return data_;
    }

    size_t length() const
    {
    return header_length + body_length_;
    }

    const char* body() const
    {
    return data_ + header_length;
    }

    char* body()
    {
    return data_ + header_length;
    }

    size_t body_length() const
    {
    return body_length_;
    }

    void body_length(size_t new_length)
    {
    body_length_ = new_length;
    if (body_length_ > max_body_length)
    body_length_ = max_body_length;
    }

    bool decode_header()//将报头的4字节字符串转换成数字
    {
    using namespace std; // For strncat and atoi.
    char header[header_length + 1] = "";
    strncat(header, data_, header_length);
    body_length_ = atoi(header);
    if (body_length_ > max_body_length)
    {
    body_length_ = 0;
    return false;
    }
    return true;
    }

    void encode_header()//把数据部分大小编码成字符串
    {
    using namespace std; // For sprintf and memcpy.
    char header[header_length + 1] = "";
    sprintf(header, "%4d", body_length_);
    memcpy(data_, header, header_length);
    }

    private:
    char data_[header_length + max_body_length];
    size_t body_length_;
    };

    #endif // CHAT_MESSAGE_HPP
    聊天客户端chat_client.cpp

    ///////////////////////////////////////////////////////////////////////////////////////////////////////
    <h3>
    </h3><h3>
    <span style="white-space:pre-wrap">聊天客户端chat_client.cpp</span>
    </h3>
    <pre>
    ///////////////////////////////////////////////////////////////////////////////////////////////////////
    //
    // chat_client.cpp
    // ~~~~~~~~~~~~~~~
    //
    // Copyright (c) 2003-2013 Christopher M. Kohlhoff (chris at kohlhoff dot com)
    //
    // Distributed under the Boost Software License, Version 1.0. (See accompanying
    // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
    //
    //boost开发文档中实时聊天程序的客户端
    //实现的大致思路是:在创建的客户端实例中初始化socket、连接服务器端,并且不断的进行着异步读操作(从服务器端读数据)
    //在主线程中,从console中不断读取要被发送的消息,并且把这些消息post至io_service,然后进行异步写操作
    //读写socket都是用异步操作
    //这种方法不同于分别开一个读线程,一个写线程, 它的优势是线程不会一直等待读写数据,在并发数大的情况下通过异步读写能提高资源利用率


    #include <cstdlib>
    #include <deque>
    #include <iostream>
    #include <boost/bind.hpp>
    #include <boost/asio.hpp>
    #include <boost/thread/thread.hpp>
    #include "chat_message.hpp"

    using boost::asio::ip::tcp;

    typedef std::deque<chat_message> chat_message_queue;

    class chat_client
    {
    public:
    chat_client(boost::asio::io_service& io_service,
    tcp::resolver::iterator endpoint_iterator)
    : io_service_(io_service),
    socket_(io_service) //使得成员函数能直接使用这些变量
    {
    boost::asio::async_connect(socket_, endpoint_iterator,
    boost::bind(&chat_client::handle_connect, this,
    boost::asio::placeholders::error)); //所有的操作都采用异步的方式
    }

    void write(const chat_message& msg)
    {
    io_service_.post(boost::bind(&chat_client::do_write, this, msg)); //将消息主动投递给io_service
    }

    void close()
    {
    io_service_.post(boost::bind(&chat_client::do_close, this)); //这个close函数是客户端要主动终止时调用 do_close函数是从服务器端
    //读数据失败时调用
    }

    private:

    void handle_connect(const boost::system::error_code& error)
    {
    if (!error)
    {
    boost::asio::async_read(socket_,
    boost::asio::buffer(read_msg_.data(), chat_message::header_length), //读取数据报头
    boost::bind(&chat_client::handle_read_header, this,
    boost::asio::placeholders::error));
    }
    }

    void handle_read_header(const boost::system::error_code& error)
    {
    if (!error && read_msg_.decode_header()) //分别处理数据报头和数据部分
    {
    boost::asio::async_read(socket_,
    boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),//读取数据包数据部分
    boost::bind(&chat_client::handle_read_body, this,
    boost::asio::placeholders::error));
    }
    else
    {
    do_close();
    }
    }

    void handle_read_body(const boost::system::error_code& error)
    {
    if (!error)
    {
    std::cout.write(read_msg_.body(), read_msg_.body_length()); //输出消息
    std::cout << " ";
    boost::asio::async_read(socket_,
    boost::asio::buffer(read_msg_.data(), chat_message::header_length), //在这里读取下一个数据包头
    boost::bind(&chat_client::handle_read_header, this,
    boost::asio::placeholders::error)); //完成一次读操作(处理完一个数据包) 进行下一次读操作
    }
    else
    {
    do_close();
    }
    }

    void do_write(chat_message msg)
    {
    bool write_in_progress = !write_msgs_.empty(); //空的话变量为false
    write_msgs_.push_back(msg); //把要写的数据push至写队列
    if (!write_in_progress)//队列初始为空 push一个msg后就有一个元素了
    {
    boost::asio::async_write(socket_,
    boost::asio::buffer(write_msgs_.front().data(),
    write_msgs_.front().length()),
    boost::bind(&chat_client::handle_write, this,
    boost::asio::placeholders::error));
    }
    }

    void handle_write(const boost::system::error_code& error)//第一个消息单独处理,剩下的才更好操作
    {
    if (!error)
    {
    write_msgs_.pop_front();//刚才处理完一个数据 所以要pop一个
    if (!write_msgs_.empty())
    {
    boost::asio::async_write(socket_,
    boost::asio::buffer(write_msgs_.front().data(),
    write_msgs_.front().length()),
    boost::bind(&chat_client::handle_write, this,
    boost::asio::placeholders::error)); //循环处理剩余的消息
    }
    }
    else
    {
    do_close();
    }
    }

    void do_close()
    {
    socket_.close();
    }

    private:
    boost::asio::io_service& io_service_;
    tcp::socket socket_;
    chat_message read_msg_;
    chat_message_queue write_msgs_;
    };

    int main(int argc, char* argv[])
    {
    try
    {
    if (argc != 3)
    {
    std::cerr << "Usage: chat_client <host> <port> ";
    return 1;
    }

    boost::asio::io_service io_service;

    tcp::resolver resolver(io_service);
    tcp::resolver::query query(argv[1], argv[2]); //输入ip(或域名)和端口号
    tcp::resolver::iterator iterator = resolver.resolve(query);

    chat_client c(io_service, iterator);

    boost::thread t(boost::bind(&boost::asio::io_service::run, &io_service));

    char line[chat_message::max_body_length + 1];
    while (std::cin.getline(line, chat_message::max_body_length + 1))
    {
    using namespace std; // For strlen and memcpy.
    chat_message msg;
    msg.body_length(strlen(line));
    memcpy(msg.body(), line, msg.body_length());
    msg.encode_header();
    c.write(msg);
    }

    c.close();
    t.join();
    }
    catch (std::exception& e)
    {
    std::cerr << "Exception: " << e.what() << " ";
    }

    return 0;
    }
    聊天服务器端chat_server.cpp

    //
    // chat_server.cpp
    // ~~~~~~~~~~~~~~~
    //
    // Copyright (c) 2003-2013 Christopher M. Kohlhoff (chris at kohlhoff dot com)
    //
    // Distributed under the Boost Software License, Version 1.0. (See accompanying
    // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
    //
    //服务器端程序,首先开启一个chat_server,用来初始话io_service和chat_room; 服务器每次只开启一个chat_room,chat_room的作用是 1//.保存用户信息 2.实现用户的join和leave 3.保存从每个客户端接收到的信息 4.将接收到的消息挂到每一个客户端write_msgs队尾
    //每连接上一个客户端(socket)就开启一个新的chat_session 并加入唯一的chat_room chat_session中实现分别对每一个客户端的异步读写//操作

    #include <algorithm>
    #include <cstdlib>
    #include <deque>
    #include <iostream>
    #include <list>
    #include <set>
    #include <boost/bind.hpp>
    #include <boost/shared_ptr.hpp>
    #include <boost/enable_shared_from_this.hpp>
    #include <boost/asio.hpp>
    #include "chat_message.hpp"

    using boost::asio::ip::tcp;

    //----------------------------------------------------------------------

    typedef std::deque<chat_message> chat_message_queue;

    //----------------------------------------------------------------------

    class chat_participant
    {
    public:
    virtual ~chat_participant() {}
    virtual void deliver(const chat_message& msg) = 0; //后面需要重载
    };

    typedef boost::shared_ptr<chat_participant> chat_participant_ptr;

    //----------------------------------------------------------------------

    class chat_room
    {
    public:
    void join(chat_participant_ptr participant)
    {
    participants_.insert(participant);
    std::for_each(recent_msgs_.begin(), recent_msgs_.end(),
    boost::bind(&chat_participant::deliver, participant, _1));
    }

    void leave(chat_participant_ptr participant)
    {
    participants_.erase(participant);
    }


    //将从某个客户端收到的消息挂到 每一个客户端的write_msgs队尾 具体见chat_participant::deliver

    void deliver(const chat_message& msg)

    {
    recent_msgs_.push_back(msg);
    while (recent_msgs_.size() > max_recent_msgs)
    recent_msgs_.pop_front(); //room中保存的消息数有限

    std::for_each(participants_.begin(), participants_.end(),
    boost::bind(&chat_participant::deliver, _1, boost::ref(msg)));
    }

    private:
    std::set<chat_participant_ptr> participants_;//用set来保存用户信息
    enum { max_recent_msgs = 100 };
    chat_message_queue recent_msgs_;//用来保存从某个客户端接收到的信息
    };

    //----------------------------------------------------------------------

    class chat_session
    : public chat_participant,
    public boost::enable_shared_from_this<chat_session>
    {
    public:
    chat_session(boost::asio::io_service& io_service, chat_room& room)
    : socket_(io_service),
    room_(room)
    {
    }

    tcp::socket& socket()
    {
    return socket_;
    }

    void start()//每生成一个新的chat_session都会调用
    {
    room_.join(shared_from_this());
    boost::asio::async_read(socket_,
    boost::asio::buffer(read_msg_.data(), chat_message::header_length),
    boost::bind(
    &chat_session::handle_read_header, shared_from_this(),
    boost::asio::placeholders::error)); //异步读客户端发来的消息
    }

    void deliver(const chat_message& msg)
    {
    bool write_in_progress = !write_msgs_.empty();
    write_msgs_.push_back(msg); //把room中保存的消息挂到write_msgs队尾
    if (!write_in_progress)
    {
    boost::asio::async_write(socket_,
    boost::asio::buffer(write_msgs_.front().data(),
    write_msgs_.front().length()),
    boost::bind(&chat_session::handle_write, shared_from_this(),
    boost::asio::placeholders::error));
    }
    }

    void handle_read_header(const boost::system::error_code& error)
    {
    if (!error && read_msg_.decode_header())
    {
    boost::asio::async_read(socket_,
    boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),
    boost::bind(&chat_session::handle_read_body, shared_from_this(),
    boost::asio::placeholders::error));
    }
    else
    {
    room_.leave(shared_from_this());
    }
    }

    void handle_read_body(const boost::system::error_code& error)
    {
    if (!error)
    {
    room_.deliver(read_msg_);
    boost::asio::async_read(socket_,
    boost::asio::buffer(read_msg_.data(), chat_message::header_length),
    boost::bind(&chat_session::handle_read_header, shared_from_this(),
    boost::asio::placeholders::error));
    }
    else
    {
    room_.leave(shared_from_this());
    }
    }

    void handle_write(const boost::system::error_code& error)
    {
    if (!error)
    {
    write_msgs_.pop_front();
    if (!write_msgs_.empty())
    {
    boost::asio::async_write(socket_,
    boost::asio::buffer(write_msgs_.front().data(),
    write_msgs_.front().length()),
    boost::bind(&chat_session::handle_write, shared_from_this(),
    boost::asio::placeholders::error)); //服务器端将收到的消息送给所有的客户端(广播的方式)
    }
    }
    else
    {
    room_.leave(shared_from_this());
    }
    }

    private:
    tcp::socket socket_;
    chat_room& room_;
    chat_message read_msg_;
    chat_message_queue write_msgs_;
    };

    typedef boost::shared_ptr<chat_session> chat_session_ptr;

    //----------------------------------------------------------------------

    class chat_server
    {
    public:
    chat_server(boost::asio::io_service& io_service,
    const tcp::endpoint& endpoint)
    : io_service_(io_service),
    acceptor_(io_service, endpoint) //全局只有一个io_service和一个acceptor
    {
    start_accept();
    }

    void start_accept()
    {
    chat_session_ptr new_session(new chat_session(io_service_, room_));
    acceptor_.async_accept(new_session->socket(),
    boost::bind(&chat_server::handle_accept, this, new_session,
    boost::asio::placeholders::error));
    }

    void handle_accept(chat_session_ptr session,
    const boost::system::error_code& error)
    {
    if (!error)
    {
    session->start();
    }

    start_accept(); //每连接上一个socket都会调用
    }

    private:
    boost::asio::io_service& io_service_;
    tcp::acceptor acceptor_;
    chat_room room_; //chat_room中没有重载构造函数 所以会直接调用默认构造函数
    };

    typedef boost::shared_ptr<chat_server> chat_server_ptr;
    typedef std::list<chat_server_ptr> chat_server_list;

    //----------------------------------------------------------------------

    int main(int argc, char* argv[])
    {
    try
    {
    if (argc < 2)
    {
    std::cerr << "Usage: chat_server <port> [<port> ...] ";
    return 1;
    }

    boost::asio::io_service io_service;

    chat_server_list servers;
    for (int i = 1; i < argc; ++i)
    {
    using namespace std; // For atoi.
    tcp::endpoint endpoint(tcp::v4(), atoi(argv[i]));
    chat_server_ptr server(new chat_server(io_service, endpoint));
    servers.push_back(server);
    }

    io_service.run();
    }
    catch (std::exception& e)
    {
    std::cerr << "Exception: " << e.what() << " ";
    }

    return 0;

  • 相关阅读:
    NetCore
    OAuth授权
    Vue混入:全局混入
    Vue作用域插槽:用作循环结构的模版
    Vue作用域插槽:基本用法
    Effect Hook
    State Hook
    表单组件中state依赖props
    Vue自定义指令
    Vue访问子组件实例或子元素
  • 原文地址:https://www.cnblogs.com/ly570/p/10961073.html
Copyright © 2011-2022 走看看